Total joint replacement, particularly total hip and knee replacement, is being performed at an increasing rate. However, it is estimated that about 10% of these joints fail at the end of ten years, with an increased failure rate with longer years of implantation. In many total joint replacements, the implant is fixed to the patient's bone with the help of bone cement (for example, polymethylmethacrylate). In the revision surgery, the removal of the existing implant, reconstruction of the bone-stock and achievement of a stable fixation with a new component is often a difficult procedure. Bone cement is sometimes firmly bonded to the implant and surrounding bone, making it a technically demanding process to remove the implant without damaging the bone. For un-cemented hip and other joints, the implant is again firmly fixed to the bone, often due to on-growth of bony tissue onto the surface of the metal implant. The goal of such revision surgery is to remove the implant with minimum damage to the bone tissue so that the replacement implant is provided with sufficient support. Sometimes the difficulty in removing an implant causes the bone to fracture, and occasionally implant removal requires the surgeon to cut the bone itself to remove the implant.
Thus, the removal of orthopedic implants during revision surgery typically involves tissue destruction, long operative times and the use of great force with tools such as a slide hammer. Even poorly fixed orthopedic implants may be very difficult to remove because of adherent soft tissue that may be difficult to reach using bone sparing operative procedures. This process of implant removal is time consuming and difficult for the surgeon. This has made reversibility a central design feature of orthopedic implants where enhanced bone fixation technologies are not employed due to resulting difficulties in removal if required (as in, for example, fully porous coated stems). The force required to remove orthopedic implants can result in destruction of local bone stock making revision of an implant much harder, longer and subject to greater health risks to the patient, including an increased incidence of, for example, blood clots and stroke.